The waterjet cutting machine is a real revolution in the metalworking industry. It offers many advantages for machining parts, such as lower production costs and the preservation of the materials being worked. But what is this innovative technology and how does it work?
Waterjet cutting: what is it?
Of all machining processes, waterjet cutting is one of the newest in industry. It has been gaining popularity in recent years thanks to the versatility of the process, which can cut different materials such as metals or glass.
As its name suggests, a waterjet cutting machine machines parts using water pressure to make the cut. This is possible thanks to the speed and power the water acquires when it strikes the surface being worked. It is a mechanical process capable of cutting any material (metals, glass, wood, textiles and so on). The results are of high quality and the desired finish is achieved.
The waterjet cutting process
The waterjet cutting machine is numerically controlled, which makes the process even simpler and easier. The first step is to set up the part to be cut on a computer using a CAD program to define the dimensions, thickness and material. The data are then processed by CAM software integrated into the machine.
The processed file is opened directly on the machine’s computer, where a series of parameters can be set, including the material properties. The material is then positioned on the machine and the machine is started. It is best to position the part so as to avoid wasting raw material. When the machine has several cutting heads, placing the part well makes it possible to carry out several cutting operations simultaneously: this helps speed up the process and reduce production costs.
These machines work continuously, so there is no need to stop the machine unless the part needs to be repositioned.
How does a waterjet cutting machine work?
A waterjet cutting machine works with a pressurised jet of water. The water comes out through a nozzle with a diameter of between 0.1 mm and 0.4 mm. But the machine does not simply spray water: the cut is made using a mixture of water and an abrasive, at very high pressure.
The nozzle plays a key role in waterjet machining, since the coherence of the jet depends on it, and this determines whether the technique being applied is viable. For example, if the jet comes out in a cone shape, cutting intensity is lost, as are precision and quality.
The pressure of the water jet also plays a very important role in this process. The right pressure is achieved with a pump fitted with a pressure intensifier, which reaches 4,000 bar. Lower pressures can be used depending on the workpiece, and it is even possible to work without mixing the water with abrasive. For marking, grooving or engraving, for example, low-pressure water is used.
Cutting speed is also essential and depends on the pump pressure, the quantity and quality of the abrasive used, the thickness of the part, the capacity of the intensifier and the diameter of the nozzle. The water can, for example, exit at speeds of up to 1,000 metres per second.
Why is abrasive added to the process? Simply because water alone is not enough to make the cut; that is why the abrasive is also key in waterjet cutting. Unless the material is soft or only engraving is required, abrasive is needed. For clay and glass composites, abrasive is essential.
Advantages of waterjet cutting
The advantages of using a waterjet cutting machine include:
- It is a cold process that adds no heat, so there is no risk of the workpiece material deforming.
- It is environmentally friendly, as no gases are released.
- The waterjet cutting machine is easy to use and requires no specialist other than the person who designs the part, who can also position the part and run the program.
- Offcuts from other jobs can be reused.
- It can cut very thick materials.
- It does not generate residual stresses.
- Low cost.